In the Introduction to his very fascinating book, Underworld: The Mysterious Origins of Civilization, published in 2002, Graham Hancock presents the theory that the worldwide myths of a Great Flood, which are told in every corner of the world, will soon be accepted as established scientific fact. He contends that between 17,000 and 8,000 years ago, the earth underwent a series of tremendous cataclysms, which transformed the planet. Modern humans who, according to science, had already existed for around 200,000 years, had been around long enough to have evolved a high civilization, which was destroyed during these cataclysms. The remains of their extremely ancient cities are now to be found submerged under the oceans.

At the end of the last Ice Age, the enormous glaciers which covered much of the land masses of the earth, melted, causing sea levels worldwide to rise many meters. Since then, as now, humans tended to concentrate their populations on the seashores, when the glaciers melted and the seas rose, these cites were submerged, and their existence forgotten, except in myth and legend.

In recent decades, many of these ancient ruins under the seas have come to light. As a diver, Graham Hancock has explored many of them himself – and these explorations form the topics of Underworld. They are controversial; in some cases, it is unclear whether they are natural rock formations or whether they are manmade. When the ancient ruins are clearly manmade, not natural, often their dates are very much in dispute.

His first example is the ruins found in the Bay of Bengal, off the east coast of India, near Nagapattinam, which were investigated by the National Institute of Oceanography (NIO) in the early 1990’s. The investigation was headed by well-known and widely-respected marine archaeologist T.C.S. Rao, who Graham Hancock interviewed several years later.

In the Bay of Bengal, five kilometers out to sea, at a depth of 23 meters, lies a horseshoe shaped manmade structure, surrounded by walls that are one meter thick and two meters high. There are at least three structures there, perhaps more. 23 meters is over 70 feet deep. According to oceanographers investigating underwater ruins on the other side of India, off the western coast, 10,000 BCE would have been the date for ruins found there at the Gulf of Kutch at 60 feet below the surface of the water. The water level would be the same on both coasts of India, so the Bay of Bengal structures must also extend back to around 10,000 BCE. These structures off the coast of Nagapattinam are incredibly old – far older than any traditional dates for the beginning of civilization.

Underworld is a lengthy and complex book, filled with many details. In it Graham Hancock also writes about his dives around the rock structures known as Yonaguni off the coast of Japan. It has not been definitely determined whether or not these are manmade. He also writes extensively about the ancient temples of Malta – and about a number of other sites around the world which, it seems, are “impossibly” old.

Since Graham Hancock wrote Underworld eleven years ago, the body of evidence that there were extremely ancient civilizations, far older than any we could have imagined just a couple of decades ago, has only grown and grown. The case for high civilizations which once existed, the ruins of which sank beneath the waves, is gaining strength as every year passes.